Are microemulsion thermodynamically stable?

Microemulsions, being thermodynamically stable systems, with low viscosity and elegant in appearance have attracted interest not only for the delivery of single drug substances with low water solubility but for the stabilization of drugs in combination due to their preferential solubility in either the water or oil …

Which is thermodynamically stable formulation?

Microemulsions are stable for relatively long periods. Microemulsions are recognized as a thermodynamically stable system. Microemulsion-based formulations are prepared in liquid forms, which are preferable for patients with difficulties in swallowing solids.

How is a microemulsion formed?

A microemulsion is a cloudy colloidal system of micron size droplets of one immiscible liquid dispersed in another, such as oil in water, in the presence of a suitable surfactant and a co-surfactant. A microemulsion is formed by vigorous stirring or sonication and is thermodynamically stable.

Why microemulsions are thermodynamically stable?

Micro-emulsion is thermodynamically stable as its Gibbs free energy caused by some effects becomes negative. Then the micro emulsion become thermodynamically stable.

Why nano emulsion is thermodynamically unstable?

Nanoemulsion is thermodynamically unstable, which means that the free energy of nanoemulsion is higher than the free energy of the separate phases (oil and water). For microemulsion, this condition is opposite.

What will be the composition of primary emulsion?

The primary emulsion formed with 4 parts by volume of fixed oil, 2 parts by volume of water and 1 part by weight of acacia (4 : 2 : 1) method.

Why is microemulsion used?

Microemulsions can carry water-soluble drugs into aqueous phase, and hence demonstrate the ability to carry both lipophilic as well as hydrophilic drugs. Microemulsions have a wide range of applicability, as they can be delivered by all major routes of drug delivery (Garg and Goyal 2014bGarg T, Goyal AK.

Which of these emulsion is more stable?

Emulsions that have smaller size droplets will generally be more stable. For water separation, drops must coalesce—and the smaller the drops, the greater the time to separate. The droplet-size distribution affects emulsion viscosity because it is higher when droplets are smaller.

How are microemulsions related to thermodynamic stability?

Microemulsions are thermodynamically stable, and their formation is facilitated by the ultralow interfacial tension of these systems, which leads to the formation of extremely small droplets of the dispersed phase. These microemulsions can take different forms which include, among others, oil, water, and oil/water bicontinuous microemulsions.

How are the three types of microemulsions prepared?

They are prepared by simple mixing of the components and do not require specific preparation conditions. There are three kinds of microemulsions: oil dispersed in water (o/w), water dispersed in oil (w/o), and bicontinuous. The presence of o/w droplets is likely to be a characteristic of microemulsions where the amount of oil is low.

What is the phase behaviour of a microemulsion?

Phase Behaviour of Microemulsion  The phase behaviour of simple microemulsion system composing oil, water and surfactant can be studied with the aid of ternary phase diagram. 11/21/2014 14 15. Continue… 11/21/2014 15 16.

Why are O / W droplets found in microemulsions?

The presence of o/w droplets is likely to be a characteristic of microemulsions where the amount of oil is low. In contrast, the existence of w/o droplets is a characteristic of microemulsions where the water fraction is low.